The objective of this research is to characterize segmental morphogenetic fields in the integument of a decapod crustacean, the crayfish. Preliminary studies have shown that in crayfish, as in insects, central segments of legs embody equivalent segmental fields. The proposed work will examine the correspondence between the leg segmental field and 1) fields in segments of bifurcating (biramous) appendages; 2) fields in terminal segments of legs; 3) fields in body segments. The method used is to graft patches of integument and observe the subsequent patterns of regeneration. Results will be compared with predictions obtained with the polar co-ordinate model of French, Bryant, and Bryant (Science 193: 969, 1976) and with a generalization of this model, the role of normal neighbors, developed by the principal investigator. Results of this study will be relevant to problems of pattern formation in vertebrates as well as arthropods.